Measurement Of Streaming Potential Coupling Coefficient On Carbonate Rocks For Downhole Monitoring In Smart Wells
DOI:
https://doi.org/10.11113/jt.v56.902Abstract
Telaga pintar merujuk kepada telaga yang mengandungi downhole sensors dan injap kawalan aliran masuk (ICV) yang dipasang pada tiub pengeluaran. Telaga ini membenarkan pengendali untuk merekodkan kadar aliran bendalir, suhu dan tekanan yang berterusan semasa pengeluaran. Baru–baru ini, pengukuran streaming potential dalam telaga pintar telah dicadangkan untuk memantau pencerobohan air. Walau bagaimanapun, masih terdapat ketidakpastian yang signifikan yang dikaitkan dengan tafsiran ukuran, terutamanya mengenai pekali gandingan streaming potential. Ini adalah ciri petrofizik utama yang menentukan magnitud streaming potential untuk potensi bendalir yang tertentu. Magnitud streaming potential pada asasnya berkait dengan kadar aliran bendalir, sifat–sifat bendalir (khususnya kemasinan), dan sifat–sifat matriks batuan. Pekali gandingan telah diukur secara uji kaji dalam teras batu pasir yang tepu dengan kemasinan air garam yang berbeza, tetapi sangat sedikit hasil ujikaji telah diterbitkan bagi batuan karbonat. Bilangan reservor karbonat yang besar di seluruh dunia menyarankan bahawa pengukuran streaming potential dalam batuan karbonat juga penting. Dalam kajian ini, kami kemukakan nilai pekali gandingan streaming potential bagi batu karbonat yang tepu dengan berbagai kemasinan air garam. Seperti yang kami jangkakan, streaming potential bagi teras itu adalah kecil tetapi masih boleh diukur, dan kemasinan yang lebih tinggi memberikan pekali gandingan streaming potential yang lebih kecil. Keputusan yang diperolehi adalah konsisten hasil penggunaan elektrod yang direka khas dan ujikaji pam berpasangan untuk menghapuskan potensi elektrik palsu. Kami mendapati bahawa pekali gandingan streaming potential di dalam batu karbonat adalah lebih rendah berbanding dengan yang ada di teras batu pasir yang ditepukan dengan kemasinan air garam yang sama. Pemerhatian ini boleh dijelaskan dengan membandingkan perbezaan titik caj sifar (pzc) di antara kedua–dua jenis batu. Secara kualitatif, hasil ujikaji menunjukkan bahawa pengukuran streaming potential boleh digunakan untuk memantau pencerobohan air di dalam reservor karbonat, sama seperti ia digunakan untuk reservor batu pasir. Kata kunci: Streaming potential; elektrokinetik; pemantauan bawah telaga; telaga pintar; water encroachment; kawalan pengeluaran air; batu karbonat Smart wells refer to wells containing downhole sensors and inflow control valves (ICV) mounted on the production tubing. These wells allow the operator to record fluid flow rates, temperature and pressure incessantly. Recently, streaming potential measurement in smart wells has been proposed to monitor water encroachment. However, there are still significant uncertainties associated with the interpretation of the measurements, particularly concerning the streaming potential coupling coefficient. This is a key petrophysical property that dictates the magnitude of the streaming potential for a given fluid potential. Streaming potential magnitude is basically related to the fluid flow rate, fluid properties (particularly salinity), and the rock matrix properties. The coupling coefficient has been measured experimentally in sandstone cores saturated with different brine salinities, but very little works have been published on carbonate rocks. The huge number of carbonate reservoirs around the world suggests that measurement of streaming potential in carbonate rocks is also important. In this study, we present value of streaming potential coupling coefficient in a carbonate rock saturated with various salinities of brine. As we expected, streaming potential in such core is small but measurable and higher salinity gives smaller streaming potential coupling coefficient. Consistent results are obtained using specially designed electrodes and paired pumping experiments to eliminate spurious electrical potentials. We noticed that streaming potential coupling coefficient in carbonate rock is lower compared to the one in sandstone cores saturated with the same salinity of brine. This observation could be explained by comparing the difference in Point of zero charges (pzc) between those two types of rock. Qualitatively, the result suggests that measurements of streaming potential could be applied for monitoring water encroachment in carbonate reservoirs, in the same manner it is applied for sandstones reservoirs. Key words: Streaming potential; electrokinetics; downhole monitoring; intelligent wells; water encroachment; produced water control; carbonate rocksDownloads
Published
2012-03-21
Issue
Section
Science and Engineering
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How to Cite
Measurement Of Streaming Potential Coupling Coefficient On Carbonate Rocks For Downhole Monitoring In Smart Wells. (2012). Jurnal Teknologi, 56(1), 87–99. https://doi.org/10.11113/jt.v56.902